U.S. patent application number 15/324331 was filed with the patent office on 2017-08-17 for locking plate system for treatment of fracture of distal radius.
The applicant listed for this patent is National University Corporation Nagoya University, Nipro Corporation. Invention is credited to Shunichi Bandoh, Tatsuya Hara, Hitoshi Hirata, Hidemasa Yoneda.
Application Number | 20170231673 15/324331 |
Document ID | / |
Family ID | 55064281 |
Filed Date | 2017-08-17 |
United States Patent
Application |
20170231673 |
Kind Code |
A1 |
Hirata; Hitoshi ; et
al. |
August 17, 2017 |
Locking Plate System for Treatment of Fracture of Distal Radius
Abstract
Provided is a locking plate system for treatment of a distal
radius fracture, including a locking plate (4) that is a flat
laminate of intermediate molding materials that includes carbon
fibers as a reinforcing material and thermoplastic resin as a
matrix; a screw anchor (5) having a shaft portion (10) which has a
principal thread (13) achieving a self-tapping action formed
thereon and an outer circumference of a head portion of the screw
anchor (5) which has an auxiliary thread (13) achieving a
self-tapping action tapped thereon; and a through-hole (6) in the
radius locking plate (4), which allows the radius main body (3) and
the fractured bone piece (2) to be threadably fixed to the radius
locking plate (4) and having a diameter that is oversized relative
to the principal thread (11), and that is undersized relative to
the auxiliary thread (13).
Inventors: |
Hirata; Hitoshi; (Aichi,
JP) ; Hara; Tatsuya; (Aichi, JP) ; Yoneda;
Hidemasa; (Aichi, JP) ; Bandoh; Shunichi;
(Gifu, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National University Corporation Nagoya University
Nipro Corporation |
Aichi
Osaka |
|
JP
JP |
|
|
Family ID: |
55064281 |
Appl. No.: |
15/324331 |
Filed: |
July 9, 2015 |
PCT Filed: |
July 9, 2015 |
PCT NO: |
PCT/JP2015/069756 |
371 Date: |
May 2, 2017 |
Current U.S.
Class: |
606/291 |
Current CPC
Class: |
A61B 2017/00526
20130101; A61B 17/8625 20130101; A61B 17/8061 20130101; A61B
17/8057 20130101; A61B 17/8028 20130101; A61B 17/8605 20130101;
A61B 2017/00902 20130101; A61B 17/68 20130101 |
International
Class: |
A61B 17/80 20060101
A61B017/80; A61B 17/86 20060101 A61B017/86 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2014 |
JP |
2014-141511 |
Claims
1. A locking plate system for treatment of a distal radius fracture
comprising: a radius locking plate to be attached as a bridge
between a fractured bone piece and a palmer side of a radius main
body at the inside of a body for recovering a position and an
orientation of the fractured bone piece produced at a distal radius
or in a vicinity thereof and subsequently enhance bone union of the
fractured bone piece and the radius main body; and a screw anchor
used for the radius locking plate, wherein the radius locking plate
is a flat laminate of intermediate molding materials that each
include carbon fibers as reinforcing material and thermoplastic
resin as a matrix, wherein the screw anchor is made of hard metal,
a shaft portion of the screw anchor has a principal thread
achieving a self-tapping action formed thereon and an outer
circumference of a head portion of the screw anchor has an
auxiliary thread achieving a self-tapping action tapped thereon,
and wherein a diameter of a through-hole in the radius locking
plate, which allows the radius main body and the fractured bone
piece to be threadably fixed to the radius locking plate, is
oversized relative to the principal thread, and is undersized in
the through-hole in its entirety or in a its lower half portion
relative to the auxiliary thread.
2. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein an intermediate molding
material reinforced by the carbon fibers of a
45.degree.-orientation material or a .+-.45.degree.-orientation
woven cloth is used in upper and lower layers, and an intermediate
molding material reinforced by the carbon fiber of a one-direction
material or a 0.degree./90.degree.-orientation woven cloth is used
in an intermediate layer.
3. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein the through-hole has a
cylindrical shape.
4. The locking plate system for treatment of a distal radius
fracture according to claim 3, wherein the cylindrical through-hole
is oversized in an upper half portion thereof and is undersized in
a lower half portion thereof, relative to the auxiliary thread.
5. The locking plate system for treatment of a distal radius
fracture according to claim 3, wherein the cylindrical through-hole
has a circumferentially continuous thread tapped in its entirety or
its lower half portion, the circumferentially continuous thread
having a diameter to be increased by the auxiliary thread.
6. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein the through-hole has a
reverse conical frustum shape in at least its opening.
7. The locking plate system for treatment of a distal radius
fracture according to claim 6, wherein the through-hole has a
cylindrical shape and has a diameter of the lower half portion of
the through-hole, the diameter being increased by the auxiliary
thread.
8. The locking plate system for treatment of a distal radius
fracture according to claim 7, wherein the through-hole has a
circumferentially continuous thread that has a diameter to be
increased by the auxiliary thread, the circumferentially continuous
thread being tapped in the lower half portion thereof.
9. The locking plate system for treatment of a distal radius
fracture according to claim 6, wherein the through-hole has a
reverse conical frustum shape in its entirety and the through-hole
has a circumferentially continuous thread, the circumferentially
continuous thread having a diameter to be increased by the
auxiliary thread, tapped in an overall hole or a lower half portion
thereof.
10. The locking plate system for treatment of a distal radius
fracture according to claim 6, wherein the lower half portion of
the through-hole has a partially spherical shape.
11. The locking plate system for treatment of a distal radius
fracture according to claim 10, wherein an enveloping surface of
tooth tips lining on and beneath the auxiliary thread forms a
partially spherical shape.
12. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein an enveloping surface of
tooth tips lining on and beneath the auxiliary thread forms a
reverse conical frustum shape.
13. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein a PEEK resin is coated on a
surface of the principal thread of the screw anchor.
14. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein a thread pitch of the
principal thread is larger than a thread pitch of the auxiliary
thread of the screw anchor.
15. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein a thread pitch of the
principal thread is smaller than a thread pitch of the auxiliary
thread of the screw anchor.
16. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein a metal wire tracing a
contour of the radius locking plate is embedded in an edge portion
of the plate.
17. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein an intermediate molding
material is coated to a face on a radius counter-approximal face of
the flat laminate of the intermediate molding materials.
18. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein a non-reinforced resin is
applied to a face on a radius counter-approximal face of the flat
laminate of the intermediate molding materials.
19. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein a non-reinforced resin is
applied to a face on a radius approximal face of the radius locking
plate.
20. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein small protrusions are
provided on a face on a radius approximal face of the radius
locking plate.
21. The locking plate system for treatment of a distal radius
fracture according to claim 20, wherein to provide the small
protrusions, positions corresponding to the small protrusions of
the flat laminate are defined by a PEEK resin compound layer.
22. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein a lateral cross-sectional
shape of the radius locking plate is a substantially crescent
shape.
23. The locking plate system for treatment of a distal radius
fracture according to claim 1, wherein bending of the radius
locking plate is provisionally set, and wherein typical plural
radius locking plates having different lengths and different widths
are lined up as semi-finished products.
24. The locking plate system for treatment of a distal radius
fracture according to claim 23, wherein the finished product of the
radius locking plate is a bending-corrected product that is formed
by partially heating the semi-finished product to adapt a distal
point of the semi-finished product to a teardrop recess of a radius
for application.
Description
TECHNICAL FIELD
[0001] The present invention relates to a locking plate system for
treatment of a distal radius fracture and, more particularly, to a
treatment implement system that includes a radius locking plate to
be attached as a bridge between a fractured bone piece and a palmer
side of a radius main body at the inside of a body, and screw
anchors used therefor, to facilitate bone union or healing of the
fractured bone piece produced in the distal portion of the radius
with the radius main body.
BACKGROUND ART
[0002] Typical parts tending to suffer a fracture due to a
brittle-bone disease include a humerus, a radius, a vertebrae, and
a femur, and fractures of these bones are called "humeral neck
fracture", "distal radius fracture", "vertebral fracture", and
"femoral neck fracture". When a person falls down due to stumbling
or the like, distal radius fractures are caused by a fall on an
outstretched hand with the wrist in dorsi-flection or
palmar-flexion. A radius is a tubular bone that extends from an
elbow to a wrist side by side with an ulna and that has a bone
marrow cavity present therein. As depicted in FIG. 29(a), the ulna
51 is positioned on the side of the little finger (on the left) and
the radius 1 is positioned on the side of the thumb (on the
right).
[0003] The distal tip of the ulna has thereon a styloid process
that protrudes toward the side of the little finger, and the distal
tip of the radius also has thereon a styloid process 52 that
protrudes toward the side of the thumb. The radius is somewhat
shorter than the ulna while the radius is thicker than the ulna and
has a teardrop portion defining recess (which is often referred to
as "teardrop recess") 53 depicted in FIG. 29(b) formed on the
palmer side due to a protrusion of a lunate bone fossa positioned
on side opposite to that of the styloid process. The teardrop
constitutes an important portion that functions as a portion to
receive a load to the wrist.
[0004] The radius extends from the teardrop recess to the diaphysis
with a substantially rectangular column-like cross-section,
resulting in a complicated shape. Generally, there exists an
individual variation in the morphology of bones of a human body and
in the same way exists an individual variation in the morphology of
teardrop recess 53 as depicted in FIG. 30.
[0005] In a surgical operation for a fracture of the distal tip,
the attachment of the radius locking plate is not therefore easy
for the operator so that it matches its shape of the radius locking
plate with the shape of the teardrop recess and the regions in
front and in the back thereof. A flexor tendon failure is
remarkably highly likely to occur when, on the radius distal tip, a
distal portion of the radius locking plate or the vicinity thereof
interferes with the thumb flexor tendon that extends close to the
palmer side of the distal radius.
[0006] The radius locking plate replaces a splint and a cast made
of plaster or an FRP (fiber reinforced plastic) that each fix a
limb or a joint from the outside of the fracture region. This is a
plate to be directly attached to the radius that can be explored
through a volar incision at the wrist, and this plate has a length
of 5 cm to 6 cm to have a size capable of being implanted in a
living body. This plate establishes robust fixation, which also
enables early functional recovery.
[0007] Titanium, an alloy thereof, or the like that is strong and
lightweight, and that is qualified to have high body safety or
biocompatibility is used for the radius locking plate to be
implanted in a body. When it is attempted to produce the radius
locking plate as a custom-made optimal product of metal, a unique
molding mold is necessary that is matched with the shape and the
size of bones of each individual.
[0008] In this manufacturing scenario, significant increase in
production cost and lead time are inevitable. The plate is usually
produced as a ready-made product to have those of typical sizes
lined up, and reduction of the price of the product is thereby
facilitated. In a surgical operation, the plate best matching for
the individual bone is employed from the line-up, and any
individual perfect fitting cannot therefore be expected.
[0009] A practice like the above is also executed for a resin
plate. Patent Document 1 describes an example of use of PEEK with
which the body safety can be secured. During a surgical operation
executed under image intensifier (x-ray) control, a metal plate 54
has an advantage that the metal plate 54 can be clearly perceived
as depicted in FIG. 31 while the metal plate 54 has a disadvantage
that the affected site is hidden thereby. When the resin plate is
employed, the X-ray transmits through it, which enables the
position and the orientation of a fractured bone piece to be easily
perceived and the affected site can therefore be meticulously
cared.
[0010] The radius locking plate maintains the fracture reduction,
and integrally fixes the radius main body and the fractured bone
piece to each other through the plate using some screw anchors. The
screw anchors each need to be a hard and strong screw anchor that
can laterally self-tap the radius that includes the compact
cortical bone, and the cancellous bone in the bone marrow cavity.
In many cases, the screw anchors are each made of titanium or an
alloy thereof similarly to the radius locking plate.
[0011] Through-holes each for the screw anchor to advance in the
radius are provided in the radius locking plate. When a large
portion of the head portion of the screw anchor remains outside the
plate, this causes local pressing or local grazing on the flexor
tendon. Necessary is at least a head portion receiving part in each
of the holes so as to sink the head portion in the through-hole to
accommodate the head portion therein and to prevent any falling out
of the anchor. This can be coped with by simply forming a stepwise
recess while introduction of a thread mechanism is necessary in the
lower half portion of the through-hole (hereinafter, referred to as
"in-hole thread").
[0012] A thread (hereinafter, referred to as "outer circumference
thread") to be screw-fixed to the in-hole thread is naturally
formed on the outer circumference of the head portion of the screw
anchor. Enabled is the block of any falling out of the anchor
toward the side of the radius as well as any reverse-falling out
toward the palmer side. Examples of this technique are described in
Patent Document 2 and Patent Document 3.
[0013] The radius locking plate has a thickness of, for example, 2
mm to 3 mm. When the radius locking plate is made of metal, the
disposition of the in-hole thread is not impossible at all. It may
be desired that the axis line of the screw anchor directed to the
point to which the screw anchor is advanced is displaced from or
inclined against the axis line of the in-hole thread. In this case,
any falling out of the anchor can be avoided when substantial
engagement is achieved between the outer circumference thread and
the in-hole thread. Some Patent Documents listed below describe the
means for the above.
[0014] FIG. 32 depicts the state where the enveloping surface of
the tooth tips lining on and beneath the outer circumference thread
is formed to be a partial spherical surface and the tooth tip
enveloping surface of the in-hole thread is also formed to be a
partial spherical surface. These examples are described in Patent
Document 3 and Patent Document 4. A recess 55 in the center of each
of FIGS. 32(a), 32(b), and 32(c) has a petal-like shape or a
hexagonal shape seen as a planar view, and is a wrench hole to
rotate the screw anchor.
[0015] FIG. 33 depicts the state where the tooth circumference
direction of the in-hole thread 56 is formed to be intermittent,
and these examples are described in Patent Document 1 and Patent
Document 3. FIG. 34 depicts dual holes 57 each having therein a
threaded hole and a non-threaded hole partially overlapping with
each other, and the dual holes 57 are described in Patent Document
3 and Patent Document 5.
[0016] Any one of the above intends to cause the flexibility to be
achieved to enable some degree of variation of the direction of the
advancement of the screw anchor during a surgical operation. When
the in-hole thread mechanism is introduced in the PEEK resin plate,
as depicted in FIG. 33(c), a metal thread insert 58 having a tooth
circumference direction intermittent thread formed thereon is
fitted to be fixed (See Patent Document 1). This thread insert is
thinner than the plate, resulting in that disposition of the
intermittent thread is not easy or costs remarkably high.
[0017] For hard threads each made of titanium or the like,
structurally allowed looseness can be used by the non-tooth portion
while a change of engagement to vary the orientation of the screw
anchor is not necessarily made smoothly. It is not easy to advance
the screw anchor in the desired direction. With the dual hole, when
the one hole of the dual hole is inappropriate, the other hole
copes with the situation. In the case where the radius locking
plate is removed, when the engagement of the metal threads is
robust, a large operation power is necessary for releasing the
screw-fixation and this aggravates the operator. In any case, the
operator is forced to use high-level techniques and high-level
skills to achieve the engagement to vary the advancement
direction.
SUMMARY OF THE INVENTION
[0018] When it is attempted to form the radius locking plate using
a resin that has an X-ray transmission property as above, it is
desired that the in-hole thread can be formed even without the
introduction of the metal thread insert. It is also demanded that
the thread does not need to be a circumference direction
intermittent screw. There is a need for a locking plate, that has
high rigidity and a compact resin layer, that achieves high
adaptiveness in an attachment to the radius, and that can reduce
the load on a manipulation to vary the advancement direction during
the execution of a surgical operation.
[0019] The present invention was made in view of the above. An
object of the present invention is to provide a locking plate
system for treatment of a distal radius fracture, that realizes
achievement of advantages due to the fact that the radius locking
plate is formed using a resin as an essential item, further
enhancement of these advantages, compensation for the disadvantages
caused by the use of the resin on the other hand, and,
additionally, enhancement of the matching property for the metal
screw anchor and the resin plate, that is, not only blocking any
falling out of the head portion from the plate through-hole of the
screw anchor but also enhancement of the close attachment
adjustment action property between the resin plate and the
radius.
[0020] The present invention is applied to a radius locking system
that comprises a radius locking plate to be attached as a bridge
between a fractured bone piece and a palmer side of a radius main
body at the inside of a body for recovering a position and an
orientation of the fractured bone piece produced at a distal radius
or in a vicinity thereof and subsequently enhance the bone union of
the fractured bone piece and the radius main body, and a screw
anchor used therefor.
[0021] Referring to FIGS. 1 and 3, the radius locking system is
characterized in that a radius locking plate 4 is a flat laminate
of intermediate molding materials 7 that each include carbon fibers
as reinforcing material and thermoplastic resin as a matrix. A
screw anchor 5 is made of hard metal.
[0022] A shaft portion 10 of the screw anchor 5 has a principal
thread 11 formed thereon to achieve a self-tapping action and the
outer circumference of a head portion of the screw anchor 5 has an
auxiliary thread 13 tapped thereon to achieve a self-tapping
action. The diameter of a through-hole 6 provided in the radius
locking plate 4, which allows a radius main body 3 and a fractured
bone piece 2 to be threadably fixed to the radius locking plate 4
is oversized relative to the principal thread 11, and is undersized
relative to the auxiliary thread 13 in the through-hole 6 in its
entirety or in its lower half portion.
[0023] As depicted in FIG. 4, intermediate molding materials 7E
each reinforced by carbon fibers of a 45.degree.-orientation
material or a .+-.45.degree.-orientation woven cloth are used as
upper layers and lower layers, and intermediate molding materials
7A and 7D each reinforced by the carbon fibers of a one-direction
material or a 0.degree./90.degree.-orientation woven cloth are used
as intermediate layers.
[0024] The through-hole 6 has a cylindrical shape as depicted in
FIG. 1(b). As depicted in FIG. 9(e), the through-hole may be
oversized relative to the auxiliary thread 13 in its upper half
portion and also be undersized relative thereto in its lower half
portion.
[0025] As depicted in FIGS. 14(b) and 14(c), in the through-hole 6
having the cylindrical shape, a circumferentially continuous thread
38, which has a diameter to be increased by the auxiliary thread
13, is tapped in the through-hole in its entirety or in its lower
half portion.
[0026] As depicted in FIGS. 16(c) and 16(d), the through-hole 6 has
a reverse conical frustum shape at least in its opening 6b. The
lower half portion of the opening 6b may have a cylindrical shape
and have a diameter to be increased by the auxiliary thread 13. As
depicted in FIG. 19(c), the circumferentially continuous thread 38,
which has a diameter to be increased by the auxiliary thread 13,
may be tapped in the cylindrical lower half portion of the thread
38. As depicted in FIGS. 19(a) and 19(b), the circumferentially
continuous thread 38, which has a diameter to be increased by the
auxiliary thread, may be tapped in the through-hole in the entirety
or in the lower half portion of the thread 38.
[0027] As depicted in FIG. 20(b), the lower half portion of the
through-hole 6 may have a partially spherical shape. As depicted in
FIGS. 15(b) and (c), the enveloping surface of the tooth tips
lining on and beneath the auxiliary thread 13 is advantageously
formed in a partially spherical shape.
[0028] Referring to FIG. 1(b), the enveloping surface of the tooth
tips lining on and beneath the auxiliary thread 13 may have a
reverse conical frustum shape.
[0029] As depicted in FIG. 16(b), a PEEK resin 45 may be coated on
the surface of the principal thread 11 of the screw anchor 5.
[0030] As depicted in FIGS. 24(a) to 24(c), the thread pitch of the
principal thread 11 is set to be larger than the thread pitch of
the auxiliary thread 13 of the screw anchor 5 or, as depicted in
FIGS. 24(d) to 24(f), the thread pitch of the principal thread 11
is set to be smaller than the thread pitch of the auxiliary thread
13 of the screw anchor 5.
[0031] As depicted in FIG. 10(c), a metal wire 17 tracing the
contour of the radius locking plate 4 is embedded in the edge
portion of this plate.
[0032] As depicted in FIGS. 5(a) and 5(b), an intermediate molding
material 7Y is coated to the face on the radius counter-approximal
face of the flat laminate of the intermediate molding material
7.
[0033] As depicted in FIG. 3(c), a non-reinforced resin 23 is
advantageously applied to the face on the radius counter-approximal
face of the flat laminate of the intermediate molding materials 7.
In addition/otherwise, as depicted in FIGS. 3(b) and 3(c), the
non-reinforced resin 23 is applied to the face on the radius
approximal face of the radius locking plate 4.
[0034] As depicted in FIG. 2(b), a number of small protrusions 14
are provided on the face on the radius approximal face of the
radius locking plate 4. As depicted in FIG. 5(a), to provide the
small protrusions, the positions corresponding to the small
protrusions of the flat laminate 8 are defined by a layer of a PEEK
resin compound 30.
[0035] As depicted in FIG. 10(b), the lateral cross-sectional shape
of the radius locking plate 4 is formed to be a substantially
crescent shape.
[0036] As depicted in FIG. 12, as to the radius locking plate,
bending thereof is provisionally set, and typical plural radius
locking plates having different lengths and different widths are
lined up as semi-finished products 4Q. As depicted in FIG. 13, a
finished product of the radius locking plate is a bending-corrected
product that is formed by partially heating the semi-finished
product 4Q to adapt the distal point thereof to the teardrop recess
of the radius for application.
[0037] According to the present invention, a radius locking plate
having an X-ray transmission property can be acquired. During a
surgical operation executed checking a video image, visual
observation of the point to be operated is enabled and an accurate
operation is thereby realized. The resin radius locking plate is a
flat laminate of intermediate molding materials such as a prepreg
sheet, and includes compact layers that each have high rigidity and
that each include remarkably few air voids. The resin radius
locking plate has a quality that any direct threaded hole
processing is executable therefor, and after-the-fact tapping of
the thread is enabled by the self-tapping executed by the metal
screw anchor.
[0038] The diameter of the through-hole is oversized relative to
the principal thread formed on the leg portion of the screw anchor,
which enables the advancement operation to be executed associated
with no load on the insertion of the screw anchor. Further, the
diameter of the through-hole is undersized relative to the
auxiliary thread tapped on the head portion of the anchor in the
through-hole in its entirety or in its lower half portion, which
enables the auxiliary thread to advance while executing its
self-tapping and achieves the restraint force with desired
strength. In the removal process of the radius locking plate, the
load on the operator necessary for releasing the screw-fixation of
the plate is significantly reduced in view of the engagement is
done between the metal thread and the resin thread.
[0039] The radius locking plate has a thickness of, for example,
2.5 mm while the resin plate of the flat laminate allows any local
deformation even through just a little compared to a hard metal
plate such as a titanium plate. The fitting property of the radius
locking plate for the radius can be improved during the surgical
operation using the advancement operation of the screw anchor even
when any unintended gap is formed between the resin radius locking
plate and the radius.
[0040] Any stretching and shrinking of the surface layer are not
obstructed in the bending processing during heating when the
intermediate molding material reinforced by the carbon fibers of
the 45.degree.-orientation material or the
.+-.45.degree.-orientation woven cloth is used in the upper layers
and the lower layers. The radius locking plate finished product is
easily acquired that has the high fitting property achieved by the
shape correction. The intermediate molding material reinforced by
the carbon fibers of the one-direction material or the
0.degree./90.degree.-orientation woven cloth is used in the
intermediate layers constituting the portion in the vicinity of the
neutral axis of the bending, and any stretching and any shrinking
are thereby unnecessary.
[0041] The portions achieving the high tension can therefore be
actualized. The after-the-fact shape variation is enabled without
degrading any mechanical property of the plate, which allows the
radius locking plate to be acquired that has the high degree of
freedom of the molding (i.e., the desired bending rigidity and the
desired torsional rigidity distribution configuration) that
otherwise cannot be acquired with any metal plate.
[0042] When the space in the through-hole is formed to have a
cylindrical shape, the through-hole is undersized in its entirety
relative to the auxiliary thread. The auxiliary thread taps a
threaded hole that has a substantially small back clearance by the
self-tapping action thereof to the cylindrical wall face. The
undersize of the through-hole in its entirety creates the restraint
state of the desired strength associated with a significant
increase of the torque. The upper half portion of the through-hole
may be set to be oversized relative to the auxiliary thread and the
lower half of the through-hole may be set to be undersized relative
the auxiliary thread. In this case, the restraint force with the
desired strength can be achieved gradually increasing the torque by
the screw anchor that advances increasing the diameter of the lower
half portion.
[0043] In the entirety or the lower half portion of through-hole
having the cylindrical shape, the circumferentially continuous
thread enabling the screw-fixation tapping of the auxiliary thread
is formed to be undersized. The screw anchor that advances
increasing the diameter of this thread realizes the restraint force
resin with the desired strength gradually increasing the
torque.
[0044] An opening of the space in the through-hole is
advantageously formed to have the reverse conical frustum shape.
The through-hole in this case also at least partially comprises a
portion that is undersized relative to the auxiliary thread tapped
on the head portion of the screw anchor. The auxiliary thread taps
a threaded hole that has a substantially small back clearance by
the self-tapping action whose torque gradually increases against
the face having the reverse conical frustum shape.
[0045] The partial undersize of the through-hole creates the
restraint state of the desired strength reducing the increase of
the torque. The self-tapping action of the screw anchor also
enables the advancement that is inclined against the axis line of
the through-hole having the reverse conical frustum shape. Pulling
of the fractured bone piece in a convenient direction and fine
adjustment of the orientation of the fractured bone piece are
facilitated.
[0046] The through-hole having the reverse conical frustum shape
may be formed to have a cylindrical shape in its lower half
portion. The through-hole is undersized relative to the auxiliary
thread, which allows the auxiliary thread to tap the threaded hole
that has a substantially small back clearance by the self-tapping
action thereof to gradually increase the diameter of the
hole-defining wall. The tapping action of the screw anchor can also
advance to be inclined against the through-hole, and realizes
variation of the axis line of the principal thread to the desired
direction. Pulling of the fractured bone piece in a convenient
direction and fine adjustment of the orientation of the fractured
bone piece are enabled.
[0047] When the circumferentially continuous thread is tapped that
has a cylindrical shape in the lower half portion of the
through-hole and that has a diameter to be increased by the
auxiliary thread, the auxiliary thread taps a threaded hole that
has a substantially small back clearance by the self-tapping action
thereof gradually increasing the diameter of the hole-defining wall
because the through-hole is undersized relative to the auxiliary
thread. This creates the restraint state of the desired strength
reducing the increase of the torque. The tapping action of the
screw anchor can also advance to be inclined against the
through-hole, and realizes variation of the axis line of the
principal thread into the desired direction. Pulling of the
fractured bone piece in a convenient direction and fine adjustment
of the orientation of the fractured bone piece are enabled.
[0048] A form can be employed to have the circumferentially
continuous thread enabling the screw-fixation of the auxiliary
thread tapped in the entirety of the through-hole of the reverse
conical frustum shaped through-hole or the lower half portion
thereof. The through-hole is undersized relative to the auxiliary
thread, which allows the auxiliary thread to tap the threaded hole
having a substantially small back clearance by the self-tapping
action thereof that gradually increases the diameter of the
hole-defining wall.
[0049] This creates the restraint state of the desired strength
reducing the increase of the torque. The tapping action of the
screw anchor also enables the advancement that is inclined against
the through-hole, and realizes variation of the axis line of the
principal thread into the desired direction. Pulling of the
fractured bone piece in a convenient direction and fine adjustment
of the orientation of the fractured bone piece are enabled.
[0050] The upper half portion of the space in the through-hole is
advantageously formed to have the reverse conical frustum shape and
the lower half portion of the space is advantageously formed to
have the partially spherical shape. The same effect is achieved as
that of the tooth tips provided on the enveloping surface having
the reverse conical frustum shape, and the allowable extent of the
direction variation can significantly be increased.
[0051] When the enveloping surface of the tooth tips lining on and
beneath the auxiliary thread is formed to have a partial spherical
surface, the tooth tips gradually achieve the self-tapping action
to achieve the desired restraint state suppressing any rapid
increase of the torque. The advancement inclined against the
through-hole is also enabled to allow any variation of the axis
line of the principal thread into a desired direction.
[0052] When the enveloping surface of the tooth tips lining on and
beneath the auxiliary thread is formed to have a reverse conical
frustum face, the tooth tips gradually achieve the self-tapping
action to achieve the desired restraint state suppressing any rapid
increase of the torque. The advancement inclined against the
through-hole is also enabled to allow any variation of the axis
line of the principal thread into the desired direction.
[0053] When the PEEK resin is coated on the surface of the
principal thread of the screw anchor, the load of the advancement
is reduced and any breakage and any destruction of the cortical
bone are alleviated.
[0054] When the thread pitch of the principal thread of the screw
anchor is set to be larger than the thread pitch of the auxiliary
thread, the resin plate can be tightly attached to the radius
associated with the advancement of the screw anchor. This is
advantageous to facilitate the tight attachment at the point at
which the resin plate acting as a bridge is partially floated from
the radius.
[0055] The thread pitch of the principal thread may be set to be
smaller than the thread pitch of the auxiliary thread. In this
case, the resin plate can be disengaged from the radius associated
with the advancement of the screw anchor. This facilitates
isolation at the point at which the resin plate acting as the
bridge is attached too tightly to the radius, or the like, and any
blood flow disorder of the capillary blood vessels of the
periosteum can be caused to tend to be avoided by releasing the
compression caused by the tight attachment.
[0056] A metal wire tracing the contour of the radius locking plate
is embedded in the edge portion of this plate. The metal wire
appears in any X-ray image and thus acts as a marker, which enables
easy perception of the relative positional relation between the
item to be operated and the plate. Further, determination of
suitability or unsuitability of the pulling operation of the
fractured bone piece is facilitated.
[0057] When the intermediate molding material softened in advance
is coated to the face on the radius counter-approximal face of the
flat laminate of the intermediate molding material, the carbon
fiber ends appearing due to the flat stacking are covered and any
direct contact with the body can be prevented.
[0058] When the non-reinforced resin is applied to the face on the
radius counter-approximal face of the flat laminate of the
intermediate molding materials, the contact with the flexor tendon
becomes soft compared to that of the metal plate and the
interference with the flexor tendon is weakened.
[0059] When the non-reinforced resin is applied to the face on the
radius approximal face of the flat laminate of the intermediate
molding materials, the contact with the radius becomes soft
compared to that of the metal plate, and dispersion and leveling of
the force of the tight attachment on the surface of the radius tend
to be facilitated. The vital load on the epidermal layer of the
radius is also reduced.
[0060] A number of small protrusions are provided on the face on
the radius approximal face or ventral surface of the radius locking
plate. Any tight attachment of the plate to the radius over the
overall face thereof is avoided and any blood flow disorder of the
capillary blood vessels of the periosteum can be caused to tend to
be avoided.
[0061] When a PEEK resin compound layer is used for the points that
correspond to the small protrusions of the flat laminate, formation
of small recesses and small protrusions is not obstructed because
no fiber woven cloth is present. The fiber chips in the compound
reinforce the small protrusions and the resin melts to form a
recess and protrusion surface layer.
[0062] The lateral cross-sectional shape of the radius locking
plate is set to be a substantial crescent shape. The center of the
lateral cross-section of the radius locking plate can thereby be
thickened and the structure can be realized for the rigidity
against each of bending and torsion to easily be improved.
[0063] The plural typical radius locking plates having different
lengths and different widths are lined up by using semi-finished
products for which after-the-fact bending variation can be
executed. Reduction of the cost can be facilitated because the
number of the metal mold types can be suppressed. The radius
locking plate is made of thermoplastic resin, which provides a
perfectly fitting product corresponding to a custom-made product
within a short term when the radius locking plate is bent by
after-the-fact deformation.
[0064] The radius locking plate can be produced as a
bending-corrected product by partial heating, to adapt the distal
portion of the semi-finished product to the teardrop recess of the
radius to be treated. The radius locking plate is produced to be a
perfectly fitting product taking into consideration the individual
difference utilizing the property of the thermoplastic resin.
Improvement of the fitting property also avoids the possibility
that the radius locking plate is displaced toward the proximal
portion.
BRIEF DESCRIPTION OF DRAWINGS
[0065] FIG. 1 depicts components of a locking plate system for
treatment of a distal radius fracture according to the present
invention.
[0066] FIG. 1(a) is a diagram seen from the palmer side on which a
locking plate is attached to a radius to fix a fractured bone piece
onto the distal side of the radius.
[0067] FIG. 1(b) is a plate partial diagram of an example of a
screw anchor and a cylindrical through-hole portion into which the
screw anchor is inserted.
[0068] FIG. 2 depicts the radius locking plate.
[0069] FIG. 2(a) is a schematic diagram of a face on the radius
approximal face on which a number of small protrusions are
provided,
[0070] FIG. 2(b) is a front elevation diagram,
[0071] FIG. 2(c) is a front diagram, and
[0072] FIG. 2(d) is a central longitudinal cross-sectional
diagram.
[0073] FIG. 3 depicts a portion corresponds to a portion seen from
a line between III and III arrows of FIG. 14(a).
[0074] FIG. 3(a) is a cross-sectional diagram of the radius locking
plate formed by flatly laminating intermediate molding materials
and a resin compound on each other.
[0075] FIG. 3(b) is a cross-sectional diagram of the case where a
non-reinforced resin is applied to the small protrusions.
[0076] FIG. 3(c) is a cross-sectional diagram of the case where the
non-reinforced resin is applied to the overall face of the locking
plate.
[0077] FIG. 3(d) is a cross-sectional diagram of the case where the
intermediate molding materials are bent and stacked on each
other.
[0078] FIG. 4 depicts a graphic explanation of the flatly stacked
layers.
[0079] FIG. 4(a) is a diagram of the intermediate molding materials
having different fiber orientations.
[0080] FIG. 4(b) is a diagram of equal-height face layers assigned
to the intermediate molding materials.
[0081] FIG. 5 is a molding process diagram of the resin radius
locking plate.
[0082] FIG. 6 is a stretching and shrinking behavior diagram of a
fiber woven cloth in each of an upper portion layer and a lower
portion layer associated with heating and bending of the plate.
[0083] FIG. 7 depicts examples of the orientation of a reinforced
fiber in the intermediate molding material.
[0084] FIG. 7(a) is a partial diagram of a one-direction
material,
[0085] FIG. 7(b) is a partial diagram of a +45.degree.-orientation
material cut out from FIG. 7(a),
[0086] FIG. 7(c) is a partial diagram of a -45.degree.-orientation
material cut out from FIG. 7(a),
[0087] FIG. 7(d) is a partial diagram of a
0.degree./90.degree.-orientation woven cloth, and
[0088] FIG. 7(e) is a partial diagram of a
.+-.45.degree.-orientation woven cloth cut out from FIG. 7(d).
[0089] FIG. 8 is an explanatory diagram of stretching of a fiber
woven cloth in the lower portion layer associated with the heating
and bending of the plate and stretching of the
45.degree.-orientation material stacked in the reverse
direction.
[0090] FIG. 9 depicts examples of advancement of the screw anchor
of the case where the through-hole is a cylindrical space.
[0091] FIGS. 9(a) and 9(b) are process step diagrams of insertion
matching with the axis line of the hole.
[0092] FIGS. 9(c) and 9(d) are process step diagrams of insertion
inclined against the axis line of the hole.
[0093] FIG. 9(e) is a cross-sectional diagram of the case where the
upper half portion is oversized relative to an auxiliary thread and
the lower half portion is undersized relative thereto.
[0094] FIG. 10 depicts examples of the radius locking plate.
[0095] FIG. 10(a) is a perspective diagram of the plate whose point
to be valley-folded by partial heating is indicated by a chain line
for the portion of a semi-finished product corresponding to a
distal portion to adapt to a teardrop recess of the radius to be
treated.
[0096] FIG. 10(b) is a schematic diagram of an example of the case
where the lateral cross-sectional shape of the radius locking plate
is formed to be a crescent shape.
[0097] FIG. 10(c) is a schematic diagram of the radius locking
plate whose edge portion has a metal wire tracing the contour of
the plate embedded therein.
[0098] FIG. 11 is a diagram of an example of steps of recovering or
correcting the position and the orientation of the fractured bone
piece and subsequently placing of a fractured bone piece to be
adjacent to a radius main body.
[0099] FIG. 12 is a diagram of semi-finished products of the radius
locking plate lined up with typical shapes and sizes.
[0100] FIG. 13 depicts examples of the state of the heating and the
bending of the radius locking plate.
[0101] FIG. 13(a) is a schematic diagram of an example of an
apparatus to bend a thick portion.
[0102] FIG. 13(b) is an explanatory diagram of deformation of a
burr portion.
[0103] FIG. 13(c) is a diagram of an example of a burr portion
heating apparatus.
[0104] FIG. 14(a) is a plan diagram of an example of the radius
locking plate that comprises through-holes whose openings each have
a reverse conical frustum shape.
[0105] FIG. 14(b) is a partial diagram of the plate on which a
circumferentially continuous thread that has a diameter to be
increased by the auxiliary thread is tapped on the entirety of the
cylindrical through-hole, and an outer appearance of the screw
anchor facing the plate.
[0106] FIG. 14(c) is a partial diagram of the plate on which the
circumferentially continuous thread that has a diameter to be
increased by the auxiliary thread is tapped on the lower half
portion of the cylindrical through-hole and a cross-sectional
diagram of the screw anchor facing the plate.
[0107] FIG. 15 depicts examples of the shape of the screw
anchor.
[0108] FIG. 15(a) is a diagram of a dimensional relation between
the screw anchor comprising the auxiliary thread whose enveloping
surface of the tooth tips lining on and beneath of the auxiliary
thread forms the reverse conical frustum face, and the cylindrical
through-hole, and
[0109] FIGS. 15 (b) and 15(c) are cross-sectional diagrams of the
case where the enveloping surface of the tooth tips lining on and
beneath the auxiliary thread forms a partial spherical face.
[0110] FIG. 16 depicts the state where the whole or a portion of
the through-hole forms the reverse conical frustum shape.
[0111] FIG. 16(a) is a plan diagram of the radius locking
plate.
[0112] FIG. 16(b) is a cross-sectional diagram of the screw anchor
whose principal thread is coated by a resin.
[0113] FIG. 16(c) is a cross-sectional diagram of a portion of the
plate at the through-hole point and the screw anchor facing the
plate.
[0114] FIG. 16(d) is a cross-sectional diagram of the portion of
the plate whose lower half portion of the through-hole has a
cylindrical shape and the screw anchor facing the plate.
[0115] FIG. 17 is a process diagram of advancement of the screw
anchor inserted matching with the axis line of the hole when the
through-hole has the reverse conical frustum shape.
[0116] FIG. 18 is a process diagram of the advancement of the screw
anchor inserted inclined against the axis line of the hole when the
through-hole has the reverse conical frustum shape.
[0117] FIG. 19 depicts the state where the whole or a portion of
the through-hole has the reverse conical frustum shape.
[0118] FIG. 19(a) is a partial diagram of the plate whose thread
formed on the through-hole has the reverse conical frustum shape in
the entirety of the through-hole.
[0119] FIG. 19(b) is a partial diagram of the plate whose thread on
the lower half portion of the through-hole has the reverse conical
frustum shape.
[0120] FIG. 19(c) is a partial diagram of the plate whose thread on
the lower half portion of the through-hole has a cylindrical
shape.
[0121] FIG. 19(d) is a partial diagram of the plate whose lower
half portion of the through-hole has a partially spherical
shape.
[0122] FIG. 20(a) is a cross-sectional diagram of the screw anchor
whose enveloping surface of the tooth tips lining on and beneath
the screw anchor forms a partially spherical shape.
[0123] FIG. 20(b) is a cross-sectional diagram of the radius
locking plate whose through-hole upper half portion has the reverse
conical frustum shape and whose through-hole lower half portion has
a partially spherical shape.
[0124] FIG. 20(c) is a cross-sectional diagram of the screw anchor
screw-fixed to and not inclined against the radius locking
plate.
[0125] FIG. 20(d) is a cross-sectional diagram of the screw anchor
screw-fixed to and inclined against the radius locking plate.
[0126] FIG. 21(a) is a partial cross-sectional diagram of the plate
of the portion pressed to be hardened when the diameter of the
circumferentially continuous thread in the lower half portion is to
be increased by the auxiliary thread.
[0127] FIG. 21(b) is a diagram of the screw anchor screw-fitted to
the circumferentially continuous thread that has a diameter to be
increased by the auxiliary thread.
[0128] FIG. 21(c) is a diagram of the state of the screw anchor
where the auxiliary thread of the screw anchor screw-advancing in
the radius inclined against the axis line of the through-hole faces
the circumferentially continuous thread before increasing the
diameter thereof.
[0129] FIG. 21(d) is a diagram of the state of the screw anchor
where the auxiliary thread maintaining its inclination against the
axis line of the through-hole is screw-fitted to the
circumferentially continuous thread increasing the diameter
thereof.
[0130] FIG. 22(a) is a cross-sectional diagram of the through-hole
before the diameter of the circumferentially continuous thread in
the entirety of the through-hole is increased by the auxiliary
thread.
[0131] FIG. 22(b) is a cross-sectional diagram of the through-hole
after the diameter of the circumferentially continuous thread in
the entirety of the through-hole is increased by the auxiliary
thread
[0132] FIG. 22(c) is a diagram of the advancement of the screw
anchor in the state where the diameter of the upper half portion of
the circumferentially continuous thread is increased by the
auxiliary thread and that of the lower half portion is not yet
increased.
[0133] FIG. 23 depicts the undersize of the circumferentially
continuous thread.
[0134] FIGS. 23(a) and 23(b) are cross-sectional diagrams of the
through-hole whose inner diameter and the valley-bottom diameter
after the diameter increase are increased relative to those before
the diameter increase.
[0135] FIG. 23(c) is a cross-sectional diagram of the through-hole
whose valley-bottom diameter is equal but whose inner diameter
after the diameter increase is increased relative to that before
the diameter increase.
[0136] FIGS. 24(a) to 24(c) are explanatory diagrams of the state
where the radius locking plate is placed to be adjacent to the
radius when the screw anchor is advanced whose thread pitch of the
principal thread is larger than the thread pitch of the auxiliary
thread.
[0137] FIGS. 24(d) to 24(f) are explanatory diagrams of the state
where the radius locking plate is disengaged from the radius when
the screw anchor is advanced whose thread pitch of the principal
thread is smaller than the thread pitch of the auxiliary
thread.
[0138] FIG. 25 is a diagram of a fixation process for the radius
locking plate, depicted exaggerating a gap that remains in the
distal end.
[0139] FIG. 26 is a diagram of the fixation process continued from
that of FIG. 25.
[0140] FIG. 27 is a diagram of the fixation process for the radius
locking plate, depicted exaggerating a gap in the teardrop
recess.
[0141] FIG. 28 is an explanatory diagram of the state where the
radius locking plate is not displaced relative to the radius when
the screw anchor is advanced whose thread pitch of the principal
thread is equal to the thread pitch of the auxiliary thread.
[0142] FIG. 29(a) is an X-ray image of a wrist region seen from the
palmer side of the right hand and
[0143] FIG. 29(b) is an X-ray image of the recess.
[0144] FIG. 30 is a diagram of the shape of a bone end indicating
presence of the individual difference in the recess on the palmer
side due to the protrusion or the like in the lunate bone fossa of
the bone end on the distal side of the radius.
[0145] FIG. 31 discloses X-ray images of the state where a metal
radius locking plate is clearly perceived and the affected site is
thereby hidden.
[0146] FIG. 32 discloses cross-sectional diagrams of an example of
a prior art proposal according to which the enveloping surface of
the tooth tips lining on and beneath the auxiliary thread is formed
to be a partial spherical face and the enveloping surface of the
tooth tips of the thread of the lower half portion of the
through-hole is also formed to be a partial spherical face.
[0147] FIGS. 33(a) and 33(b) are cross-sectional diagrams of an
example of a prior art proposal according to which the tooth
circumference direction of the thread tapped in the through-hole is
intermittent, and
[0148] FIG. 33(c) is a partial cross-sectional diagram of a resin
plate into which a metal screw insert is fitted to be fixed.
[0149] FIG. 34 discloses cross-sectional diagrams of an example of
a prior art proposal that uses dual holes each having a hole with a
thread and a hole with no thread.
EMBODIMENTS OF THE INVENTION
[0150] A locking plate system for treatment of a distal radius
fracture according to the present invention will be described below
in detail referring to drawings having embodiments thereof depicted
therein. The present invention creates the locking plate system for
treatment of a distal radius fracture that is a ready-made product
but that achieves the compatibility with the radius matching that
of a custom-made product, by making excellent use of the detailed
analyses of various types of information on the human bone
measurement, and the recent body simulation technique.
[0151] The system is realized by, for example, facilitating use of
a composite material as the raw material of the radius locking
plate for the plate to have the structure and the mechanical
properties of the rigidity that are suitable for a surgical
implement to be implanted in a body for a bone fragility fracture
and to improve the shape compatibility. In addition, the present
invention attempts to include in the plate a restraint mechanism
that utilizes the properties of the composite material product
expecting improvement of the precision of the fixation of the
radius locking plate to a radius using a screw anchor.
[0152] FIG. 1(a) depicts an example of the radius locking plate 4
attached on the palmer side in a body to fix a fractured bone piece
2 of a distal end of a radius 1 to a radius main body 3. FIG. 1(b)
depicts an example of the radius locking plate 4 and a screw anchor
5 used therefor. As to the radius locking plate, only the vicinity
is depicted of a through-hole 6 having a cylindrical shape into
which the screw anchor is inserted. The radius locking plate 4 is
attached as a bridge to the fractured bone piece 2 and the radius
main body 3 as depicted in FIG. 1(a) to enhance the bone union of
the fractured bone piece 2 and the radius main body 3 after
recovering the position and the orientation of the fractured bone
piece produced at the distal radius or in the vicinity thereof. The
screw anchor 5 is a lug screw that advances in the radius 1 through
the through-hole 6 that is defined to be suitable for causing the
screw anchor 5 to pass through the radius locking plate.
[0153] As depicted in FIG. 2(a), the radius locking plate 4 has a
number of small protrusions 14 described later provided on the face
thereof on the radius approximal face. FIG. 2(b) is a front
elevation diagram, FIG. 2(c) is a front diagram, and FIG. 2(d) is a
central longitudinal cross-sectional diagram. The radius locking
plate 4 is a flat laminate 8 depicted in FIG. 3(a) of an
intermediate molding material 7 that includes carbon fibers as
reinforcing material and thermoplastic resin as a matrix, and is an
article formed by hot pressing forming. Examples of the
thermoplastic resin include PEEK (polyetheretherketone) and
polyetherimide, and the thermoplastic resin is non-toxic to a human
body, is softened by being heated, and is melted by being heated
further. This property is significantly different from that of a
thermoset resin that is hardened by being heated.
[0154] The intermediate molding material 7 is a prepreg sheet
completely impregnated with the resin or a semi-preg sheet that is
a half-impregnated article having a draping property, and
incorporates therein carbon fibers as the reinforcing material.
These intermediate molding materials are each formed in advance
into a plate or a sheet having a thickness of, for example, 0.2 mm
and are each cut to have a contour that is a level curve 9 of the
radius locking plate 4 as depicted in FIGS. 4(a) and 4(b). These
are stacked on each other in a metal mold, are heated and pressured
after the mold clamping, and are gradually cooled and the like, and
a hardened finished product is acquired.
[0155] With reference back to FIG. 1(b), the screw anchor 5 is made
of hard, rustproof, and robust metal that typically is titanium or
a titanium alloy, and has body safety. A shaft portion 10 thereof
has a principal thread 11 formed thereon that has a self-tapping
action to advance tapping a thread in the radius 1 by the rotation
thereof. A continuous thread 13 (hereinafter, referred to as
"auxiliary thread") achieving a self-tapping action is tapped on
the circumference of a head portion 12 thereof. To prevent any
excessive screwing, shaping the head portion 12 to have the reverse
conical frustum shape as depicted is mainly employed at present.
The auxiliary thread 13 of the present invention is however not
limited to this shape.
[0156] The through-hole 6 is oversized relative to the principal
thread 11 of the screw anchor 5, and is undersized relative to the
auxiliary thread 13 thereof. To be oversized means the hole
diameter with which the principal thread 11 can advance therein
without any screw-fixation, and no rotation force is necessary for
the principal thread 11 to be inserted into the plate. To be
undersized means the hole diameter with which the auxiliary thread
13 cannot advance without increasing the hole diameter by
self-tapping, and it is required that a rotation force is applied
to advance the auxiliary thread 13. Similarly to the feeling of the
case of a wood screw, the auxiliary thread gradually creates the
restraint state during the advancement of the radius locking plate.
Not that all the through-holes provided in the radius locking plate
need to be oversized relative to the principal threads of the screw
anchors and need to be undersized relative to the auxiliary threads
thereof.
[0157] As depicted in FIG. 3(a) and FIG. 10(b), the resin radius
locking plate 4 has the lateral cross-sectional shape that is in
principle a substantially crescent shape. To avoid any contact of
the radius locking plate with the tendon of the wrist to rupture
the tendon, the upper face needs to have smooth shape variation
and, in addition, this also is to secure the thickness with which
the head portion of the screw anchor can be accommodated. When the
central portion in the lateral cross-section of the radius locking
plate is thickened, the desired rigidity against each of bending
and torsion to be achieved by the plate also tends to be
achieved.
[0158] The crossing angle .theta. (see FIG. 10(b)) between the
plane on the radius approximal face and the plane on the radius
counter-approximal face at the end of the plate is selected to be
an angle equal to or smaller than 40.degree. as an indication while
the angle .theta. is determined taking into consideration the
proximity with the radius. In any case, occurrence of any flexor
tendon failure caused by grazing of the plate that protrudes toward
the palmer side with the flexor tendon of the thumb is avoided as
much as possible, and gentle contact and compatibility with the
tapetum difficult to be achieved by any metal plate can easily be
investigated.
[0159] As depicted in FIG. 2(b), said a number of small protrusions
14 are provided on the face on the radius approximal face as
consideration to soften the contact with the radius, that is, to
avoid any blockage against the organic activity of the periosteum.
This is based on the intention to avoid any close attachment to the
overall face of the radius and, as described later in the section
for the procedure for molding the radius locking plate, a PEEK
resin compound layer is used for the points corresponding to the
small protrusions of the flat laminate.
[0160] No woven cloth and no long fiber are present in the
compound, enables the disposition of the small recesses and
protrusions not to be obstructed. The fiber chips in the compound
reinforce the small protrusions and the resin melts to form the
recess-and-protrusion surface layer. When the close attachment to
the overall face is avoided, any blood flow disorder of the
capillary blood vessels of the periosteum is suppressed and this
contributes to avoidance of any recrosis of the periosteum.
[0161] Though the procedure for molding the radius locking plate
will be described later in detail, the overview of the procedure is
that the intermediate molding material 7 formed by impregnating
carbon fibers with PEEK and hardening these is cut into a
predetermined shape of each of the layers, the cut intermediate
molding materials 7 are stacked on each other (see FIGS. 4(a) and
4(b)), and fusion between the layers is facilitated using PEEK
eluted from the layers during heating. As depicted in FIG. 5(b), an
intermediate molding material softened in advance (a softened
prepreg sheet) 7Y is advantageously coated on the face on the
radius counter-approximal face of the flat laminate 8 (see FIG.
5(a)).
[0162] During the increase of the temperature up to about
400.degree. C. thereafter, carbon fiber cut edges 15 exposed at
ends of the layers because of the flat laminate can be wrapped up
to also be able to avoid any exposure after the molding and
hardening. When air cooling is executed after the pressuring, the
radius locking plate can be acquired that has a three-dimensionally
smooth shape, the robust strength property, the X-ray transmission
property, and the body safety. A portion 4a running off the end of
the molded article (see FIG. 10(a)) is removed when necessary by a
burr removal operation or the like in the finishing processing.
[0163] The layers of the flat laminate will be described. As
depicted in FIG. 4(a), in each of the portions to be the upper
portion layer and the lower portion layer of the radius locking
plate, an intermediate molding material 7E is used that is
reinforced by carbon fibers of a 45.degree.-orientation material or
a depicted .+-.45.degree.-orientation woven cloth allowing any
stretching and shrinking during the softening of the resin.
[0164] In the intermediate layer, an intermediate molding material
7A reinforced by carbon fibers of a one-direction material or an
intermediate molding material 7D reinforced by carbon fibers of a
0.degree./90.degree.-orientation woven cloth is used that does not
allow any stretching and any shrinking but that achieves a high
tension. For example, when nine sheets are used, the sheets are
stacked on each other in order of 7E, 7E, 7D, 7A, 7A, 7A, 7D, 7E,
and 7E.
[0165] When the intermediate molding material reinforced by the
carbon fibers of the 45.degree.-orientation material or the
.+-.45.degree.-orientation woven cloth is used in the upper portion
layer and the lower portion layer, as depicted later referring to
FIG. 13(a), the stretching and the shrinking of the surface layer
are not obstructed in the bending processing during heating. As
depicted in FIG. 6(a), when a portion of the radius locking plate 4
is somewhat bent downward, the carbon fibers in the upper portion
layer stretches in a pantagraph-way from the state of FIG. 6(b) to
the state of FIG. 6(c), and the carbon fibers in the lower portion
layer shrinks like a pantagraph-way from the state of FIG. 6(d) to
the state of FIG. 6(e). The resin of the matrix is molten or
semi-molten, which enables any deformation of the carbon fibers not
to be obstructed. Even when the resin becomes hardened by cooling,
the deformation of the carbon fibers is maintained and the
reinforcement effect by the carbon fibers therefore does not vary
at all.
[0166] The intermediate layer constitutes the vicinity of the
neutral face, which eliminates the substantial needs for any
stretching and any shrinking of the carbon fibers. The
reinforcement by the one-direction material and/or the
0.degree./90.degree.-orientation woven cloth achieving the high
tension is remarkably effective. As above, any after-the-fact shape
variation is enabled without degrading the mechanical properties of
the radius locking plate, by actualizing the portion achieving the
high tension and the portion allowing any stretching and any
shrinking. This means that the resin plate has a high degree of
freedom of the molding that cannot be achieved by any metal
plate.
[0167] A radius locking plate can be formed that has the desired
bending rigidity and the desired torsional rigidity distribution,
by changing the variation of the stacked layers. A radius locking
plate finished product can therefore be acquired that has a
remarkably high fitting property for the radius by the shape
correction. The intermediate molding material 7E depicted in FIG.
7(e) is formed by cutting the intermediate molding material 7D
reinforced by the 0.degree./90.degree.-orientation woven cloth of
FIG. 7(d) such that the fiber direction is 45.degree..
[0168] The stretching by the pantagraph-like deformation of the
carbon fiber woven cloth as depicted in FIG. 8(b) in imparting the
bending of FIG. 8(a) to the radius locking plate, has been
described referring to FIGS. 6(b) and 6(c). As depicted in FIGS.
8(c) and 8(d), the intermediate molding materials 7B and 7C may be
used that are reinforced by the 45.degree.-orientation material and
whose orientations are different from each other. These layers are
alternately stacked on each other in principle. FIG. 8 depicts the
case of the stretching while the case of the shrinking is same. The
intermediate molding materials 7B and 7C are formed by only cutting
the intermediate molding material 7A reinforced by the
one-direction material depicted in FIG. 7(a)such that the fiber
orientation becomes +45.degree. or -45.degree..
[0169] The through-hole will be described below. In this example,
the through-hole has a simple cylindrical shape. As described
referring to FIG. 1(b), the through-hole is oversized relative to
the principal thread 11 of the screw anchor 5 and is undersized
relative to the auxiliary thread 13 tapped on the head portion
thereof. The auxiliary thread advances forming a threaded hole that
has a substantially small back clearance by the self-tapping action
to the cylinder wall face and therefore creates the restraint state
of the desired strength associated with an increase of the
torque.
[0170] Though it has been described that the reverse conical
frustum shape is mainly employed at present for the head portion of
the screw anchor 5, in this case, not to mention, the enveloping
surface of the tooth tips lining on and beneath the auxiliary
thread 13 also forms a reverse conical frustum shape. The tooth
tips therefore gradually achieve the self-tapping action and
achieve the desired restraint state suppressing any rapid increase
of the torque. Any advancement inclined against the through-hole is
also enabled and any variation of the axis line of the principal
thread to the desired direction is also allowed.
[0171] In FIG. 1(b), the thread in a P-zone has no room to screw
together with the through-hole 6. During the passage of the thread
in the P-zone through the through-hole as depicted in FIG. 9(a),
the principal thread 11 of the screw anchor can advance in the
radius self-tapping the radius. During the passage of the thread in
a Q-zone through the through-hole, the auxiliary thread 13 can
gradually self-tap the through-hole 6 as depicted in FIG. 9(b).
[0172] The rotation force needs to gradually be increased. The
thread cuts into the hole-defining wall while the amount of the
produced swarf can be ignored because the extent of crumbling of
the resin wall is low. When the thread in an R-zone bites the
hole-defining wall, the advancement gradually becomes difficult.
The operator is notified of the fact that the screwing reaches its
limit. This screwing together also achieves a slacking prevention
effect.
[0173] As is understood from the above description, according to
the locking plate system for treatment of a distal radius fracture,
basically, a radius locking plate can be acquired that has the
X-ray transmission property in addition to the individual effects
described above. During a surgical operation executed based on an
image, an accurate surgical operation is realized by enabling the
visual observation of the point to be operated that overlaps with
the carbon fiber reinforced plastic (CFRP) radius locking plate.
The compact layers having high rigidity are acquired in relation to
the fact that the flat laminate using the intermediate molding
materials is used, and tapping having even quality and high
precision as much as possible is therefore enabled, that
approximates those of a metal screw anchor.
[0174] As to the molding process, the limit residue amount of air
voids 16 (see FIG. 3(d)) tends to be cleared because any bent
stacked layers of an intermediate molding material 7X (see FIGS.
7(a) to 7(c)) are not used like the one depicted in FIG. 3(d) that
closes any escapement for gas bubbles to be pushed out to the edge
for degassing. In the removal operation of the radius locking plate
executed when the bone union is achieved, the operation force
necessary for releasing the screw-fixation is significantly small
and the load on the operator is reduced because the fixation is
only biting between the metal and the resin.
[0175] The radius locking plate has a thickness of, for example,
2.5 mm while the resin radius locking plate of the flat laminate
allows local deformation even a little compared to that of a hard
metal such as titanium. Even when unintended gap is formed between
the radius locking plate and the radius, the fitting property of
the radius locking plate for the radius can be improved during the
surgical operation by the advancement operation of the screw
anchor. This will be exemplified later in detail.
[0176] As depicted in FIG. 10(c), a metal wire 17 tracing the
contour of the radius locking plate 4 is advantageously embedded in
the edge portion of this plate. The metal wire appears in X-ray
images and thus acts as a marker, which enables easy perception of
the relative positional relation between the item to be operated
and the plate, and the degree of the pulling operation of the
fractured bone piece 2 can easily be perceived. An example of the
operation execution process will be introduced referring to FIG.
11.
[0177] FIG. 11(a) depicts the uninjured radius 1 that is simply
depicted. FIG. 11(b) depicts the state where the fractured bone
piece 2 is produced at the distal end when the radius 1 is injured.
In FIG. 11(c), the radius locking plate 4 is attached to the radius
1 on the palmer side and is tentatively fixed by a screw anchor 5T.
In FIG. 11(d), a stinger 19 is inserted in one of small holes 18
(see also FIG. 11(a)) provided at a number of points of the radius
locking plate 4. In FIG. 11(e), the position and the orientation of
the fractured bone piece 2 are recovered or corrected by operating
the stinger 19. In FIG. 11(f), a screw anchor 5A is driven into the
fractured bone piece 2 to pull up the fractured bone piece 2.
[0178] In FIG. 11(g), the fractured bone piece 2 is put adjacent to
the radius locking plate 4. In FIG. 11(h), the tentatively fixing
screw anchor 5T is somewhat loosened and the radius locking plate 4
is pulled toward the elbow as indicated by an arrow 21 using a long
hole 20. In FIG. 11(i), another screw anchor 5B is driven in the
state where a gap 22 between the fractured bone piece 2 and the
radius main body 3 is narrowed. The tentatively fixing screw anchor
5T is also tightened. When the bone union is achieved as the time
elapses in the state where the fractured bone piece is put adjacent
to the radius main body, the radius locking plate is removed by
releasing the screw anchors by executing the second surgical
operation.
[0179] As depicted in FIG. 3(b), a non-reinforced resin 23 is
advantageously applied to the face on the radius approximal face of
the radius locking plate. The contact with the radius becomes soft
compared to that of the metal plate, and dispersion and leveling of
the force of the tight attachment are facilitated on the surface of
the radius. Not to mention, the vital load on the epidermal layer
of the radius is also reduced.
[0180] Execution of the same treatment for the upper and the lower
faces causes no inconvenience even for a radius locking plate 4M
having no small protrusion provided thereon as depicted in FIG.
3(c). The non-reinforced resin may be applied instead of the
intermediate molding material 7Y (see FIG. 5(b)). Any application
session is executed after the molding and the finishing processes
are completed.
[0181] The system comprising the radius locking plate and the screw
anchor has been described. Based on these ideas, the radius locking
plate is considered to be tentative taking into consideration the
bending thereof has room for after-the-fact variation thereof and,
as depicted in FIG. 12, typical plural radius locking plates having
different lengths and different widths are lined up as
semi-finished products 4Q. When the number of lined-up products is
large, some of these are usable as they are as finished
products.
[0182] When a bending corrected product partially heated is
manufactured according to the procedure of FIG. 13 from the
semi-finished products to adapt the distal end portion of the
patient for application to the teardrop recess of the radius for
application, a finished product of the radius locking plate is
acquired. This is a custom-made product that takes into
consideration the individual difference by utilizing the properties
of the thermoplastic resin.
[0183] The possibility is also resolved of shifting toward the
proximal portion by slipping caused by bad fitting (insufficient
supporting). Worry for any flexor tendon failure is alleviated
because consideration is taken to avoid any protruding of the head
portion of the screw anchor from the plate toward the palmer side
in the vicinity of the teardrop recess.
[0184] An example of the molding process of the resin radius
locking plate 4 will be described referring to FIG. 5. Such items
are used as apparatuses as an upper and a lower molding molds 25U
and 25L each including a cavity having a shape of the plate, a
heater 26 that heats the flat laminate in the molding molds
together with the molding molds, and a pressuring machine 27 that
pressures the molding molds from above and from beneath. A number
of small recesses 29 for providing the small protrusions 14 (see
FIG. 3(a)) are provided on the bottom of the cavity 28L to mold the
lower half portion of the radius locking plate.
[0185] In FIG. 5(a), the PEEK resin compound 30 is placed on the
bottom of the cavity. The prepreg pieces 7e, 7d, and 7a (see FIG.
4) are stacked thereon each cut along the level curve. The softened
prepreg sheet 7Y depicted in FIG. 5(b) is finally put on the flat
laminate 8 to cover the overall flat laminate 8. Though not
depicted, guide bars or the like are set up in the cavity when
necessary to avoid generation of any horizontal shifting among the
layers.
[0186] In FIG. 5(b), the upper mold 25U having the cavity 28U
provided therein that forms the upper half portion of the radius
locking plate is put on. In FIG. 5(c), the compound and the resin
of the prepreg pieces are melted by the heater 26 and the volume of
the layered body is gradually reduced with, in addition, the weight
of the upper mold 25U. The air among the layers at this time is
pushed to the ends of the prepreg pieces accompanying the flow of
the molten resin, and moves along the inner face of the prepreg
sheet 7Y, and degassing is executed in a mating face 25a. In this
case, though not depicted, when molding molds are placed under
vacuum as necessary, the degassing is more quickly executed.
[0187] In FIG. 5(d), the heated molding molds are moved into the
pressuring machine 27 and, in FIG. 5(e), a high pressure is
instantly applied thereto. The fused article of the prepreg and the
compound is hardened during the slow cooling and a block of
finished product is formed that has the carbon fibers forming
layers therein as depicted in FIG. 5(f). When the finishing process
is executed for this, the semi-finished products 4Q.sub.11 to
4Q.sub.13 and 4Q.sub.21 to 4Q.sub.23 of the radius locking plate
are acquired that are depicted in FIG. 10(a) or FIG. 12.
[0188] The fact that the radius has individual difference has been
described and, as depicted in FIG. 12, for the CFRP radius locking
plate, the typical plural products having different lengths,
different widths, and different bending are prepared as lined-up
products, that is, ready-made products. This achieves the purpose
of suppressing as much as possible any increase of shapes and types
of the molding molds. This is because the bending types are
suppressed to tentative one or two based on the lengths and the
widths. The process to establish the custom-made plates can be
executed only for the case of the resin plates for which the
process can be executed after-the-fact, and any molding mold is
unnecessary that specially determines the length, the width, and
the bending and that is necessary for establishing the custom-made
metal radius locking plates.
[0189] The case is also present where creation of slight bending is
enabled during execution of a surgical operation, and high
adaptability can be achieved that cannot be achieved by any metal
plate. This is also enabled not by the bent stacked layers each cut
along the mold face depicted in FIG. 3(d) but by the flat stacking
as depicted in FIG. 3(a). This is because the case is also present
where the bending rigidity properly lower than that of the metal
plate can be imparted, and this leads to nurturing of operators
that each have a high precision fitting technique.
[0190] In the present invention, a process utilizing the property
of the thermoplastic resin capable of being thermally deformed can
be executed for each of the lined-up products. This is because
local shaping by partial heating is enabled to adapt the point of
the lined-up product corresponding to the distal portion to the
recess on the palmer side on the bone distal end of the radius for
application.
[0191] When the fitting property of the radius locking plate for
the radius is degraded, the leveling of the fixation surface
pressure by the screw anchor acting on the radius is disrupted. The
presence of a low surface pressure indicates the presence of a high
surface pressure and causes a further local increase of the load on
the radius to also be a factor to delay the recovery.
[0192] Necessary are at least the following process steps for the
preparation of the semi-finished product and for making it into the
finished product. For preparing the semi-finished products of
various sizes produced as the ready-made products, X-ray CT
photograph data of the radius is summarized and the planar shapes
are statistically classified [a first step]. The main parameters
are the length and the width, and it is supposed that about four
types are assumed for each length and each width to determine, for
example, 16 kinds of standard type in total [a second step].
[0193] Resin radius locking plates matching with the dimensions and
shapes of the standard types are make-to-stock-produced [a third
step]. The recovered shape of the radius is computed from the
radius X-ray CT data of the patient suffering the fracture, and
data on bending is acquired that is suitable for being matched with
the teardrop recess of the treated radius. The strict shape and the
strict size to be imparted to the radius locking plate are
determined [a fourth step].
[0194] Shape gauges 31, 32A, and 32B (see the middle section of
FIG. 13) of a radius corresponding portion that corresponds to the
recovered shape and, when necessary, a hole opening drill guiding
tool to form the through-hole for the screw anchor are produced
using a three-dimensional printing technique [a fifth step]. The
semi-finished product 4Q is locally heated by a heating and
deforming apparatus 33 to be plastic-deformable and is processed by
bending according to the shape gauges [a sixth step]. A pilot hole
is formed in the radius using the hole opening drill guiding tool
and the radius locking plate is fixed to the radius using the screw
anchor [a seventh step].
[0195] To suppress the number of types of the semi-finished
products, the tentative number of bend patterns to be the factor to
be taken into consideration with the top priority for the fitting
is limited to, for example, only one or two for the typical bend
pattern(s). The shape of the radius of the patient is also measured
and the semi-finished product best approximating this shape is
selected. The best adapted product is created by modifying the
bending to be matched with the shape of the teardrop recess, and an
outstandingly inexpensive custom-made product is thereby
produced.
[0196] This is because of realization of reduction of the cost of
the bend modifying apparatus itself, and simplification of and
reduction of the necessary time period for the modification
operation. The radius locking plate substantially perfectly fitting
the radius achieves a remarkably excellent treatment effect.
[0197] The finished product formed by correcting the radius locking
plate is created by valley-folding or mountain-folding along any
one of chain lines 34 of FIG. 10(a). This is because the distal end
of the radius locking plate is the most delicate point in the
fitting thereof to the distal radius. As depicted in FIGS. 13(a)
and 13(c), insufficient fitting can often be avoided by applying
slight after-the-fact deformation. Though the degree of the
deformation is low, compared to the metal plate not capable of
being deformed, improvement of the positional relations with the
navicular bone and the lunar bone present in the vicinity thereof
and improvement of the compatibility with the muscle and the tendon
present between the plate and these bones are facilitated and the
physical load on the patient is therefore significantly
reduced.
[0198] To the portion 4a running off the end (See FIG. 10(a)), the
process of FIG. 13(c) is also applied when intended deformation as
depicted in FIG. 13(b) is necessary to contribute to the fitting.
These items cannot be considered with any metal radius locking
plate. It is assumed that the metal radius locking plate can even
be bent, any after-the-fact bending distorts the shapes of the
through-holes and the threads, and these holes and threads cannot
screw together with any metal screw anchor. The resin plate
presents flexible behaviors with respect to the compatibleness of
the through-holes and the hole-defining walls with the screw
anchors by the advancement of the screw anchors.
[0199] The advancement executed when the auxiliary thread of the
screw anchor advances straight in the through-hole has been
described. Referring to FIGS. 9(c) and 9(d), it can be seen that
advancement can be executed with an axis line 5a of the screw
anchor 5 not matching with the axis line 6a of the through-hole 6.
The advancement can be executed with the axis line of the screw
anchor inclined against the axis line of the through-hole. As
above, it can be stated that the thread teeth forming the reverse
conical frustum enveloping surface have a wide range of options for
the advancement direction.
[0200] This is often employed when the confidence of the fixation
of the radius locking plate to the radius is improved by causing
the advancement directions of the plural screw anchors to differ
from each other. This is exactly because the screw anchors are made
of the hard metal and the radius locking plates are each fully made
of the resin. The screwing of the screw anchor is executed through
a wrench hole 35 depicted in FIG. 9(a). An example including a
cannula 36 of a long hole along the axis line is depicted, but this
has no relation with the present invention and will not be
described.
[0201] The through-hole is undersized relative to the auxiliary
thread tapped on the head portion of the screw anchor, which allows
the tooth tips provided on the reverse conical frustum enveloping
surface to gradually achieve the self-tapping action. This in turn
creates the desired restraint state while suppressing any rapid
increase of the torque. As above, the self-tapping action of the
screw anchor also enables the advancement inclined against the
through-hole and realizes the variation of the axis line of the
principal thread to the desired direction. This also enables
pulling of the fractured bone piece in the convenient direction and
the fine adjustment of the orientation of the fractured bone
piece.
[0202] With the thread formed in the through-hole of a metal plate,
the circumference direction needs to be intermittent (see FIG. 33)
or a dual hole including a threaded hole and a hole without any
thread needs to be employed (see FIG. 34) to enable flexibility of
the advancement direction while, with the resin plate, any
preparation is unnecessary for allowing the inclined advancement.
This is also an advantage of employing the reverse conical frustum
shape for the auxiliary thread.
[0203] As depicted in FIG. 9(e), the cylindrical through-hole 6 is
oversized in its upper half portion 6U and is undersized in its
lower half portion 6L relative to the auxiliary thread. In this
case, the screw anchor that advances increasing the diameter of the
lower half portion can achieve the restraint force of the desired
strength gradually increasing the torque.
[0204] As depicted in FIGS. 14(b) and 14(c), for the cylindrical
through-hole 6, a circumferentially continuous thread 38 that has a
diameter to be increased by the auxiliary thread can be tapped on
the overall inner face or the lower half portion thereof. This
forms an entirely extending thread 38T on and beneath the
through-hole 6 or forms a partially extending thread 38P while, in
any case, the circumference direction intermittent thread (see FIG.
33) is unnecessary.
[0205] With the continuous thread that is easily tapped, the screw
anchor advances using the self-tapping only to increase the pitch
circle without varying the thread pitch. The rapid increase of the
torque in this case is suppressed relative to that of the case of
the cylindrical through-hole and, in spite of this, the restraint
state of the desired strength is created. Any metal screw insert
(see FIG. 33(c)) does not need to be introduced to introduce the
thread mechanism into the resin plate.
[0206] The behavior in each zone corresponding to FIG. 1(b) in the
case where the entirely extending thread 38T is employed can easily
be estimated from FIG. 15(a). During the passage of the thread in
the Q-zone through the entirely extending thread 38T, though not
depicted, the auxiliary thread 13 advances through the entirely
extending thread 38T. The auxiliary thread 13 self-taps the
entirely extending thread 38T to increase the diameter thereof. The
rotation force is gradually increased while the load thereof is
smaller than that in the Q-zone of FIG. 1(b).
[0207] When the thread in the R-zone bites the hole-defining wall,
the advancement gradually becomes difficult and this notifies the
operator of the fact that the screwing reaches its limit. The same
is applied to the case where the advancement is executed in the
partially extending thread 38P. In any case, the self-tapping
produces no or a substantially small amount of swarf, and
improvement of the screw-fixation strength, and strengthening and
densification of the circumference of the through-hole by
compressing the threaded hole-defining wall of the through-hole are
facilitated.
[0208] Instead of employing the cylindrical shape for the
through-hole 6, as depicted in FIG. 16(c), the through-hole 6 can
be formed to have a reverse conical frustum shape in at least its
opening 6b. As can be seen from FIG. 16(a), the diameter of the
through-hole 6 seen from the palmer side is larger than that of the
case of FIG. 14(a) and is often applied to the distal end of the
radius locking plate 4. FIG. 17 depicts the state where the screw
anchor 5 advances in the through-hole 6 of the radius locking plate
by the self-tapping that matches with the axis line of the hole,
and is screw-fixed. FIG. 18 depicts the course of the
screw-fixation of the screw anchor that advances being inclined
against the axis line of the hole.
[0209] When the through-hole has the reverse conical frustum shape
in its entirety, as depicted in FIGS. 19(a) and 19(c), the
circumferentially continuous thread 38 can be formed in the
entirety or in the lower half portion of the through-hole. The
lower half portion continued from the opening 6b having the reverse
conical frustum shape can be formed to have a cylindrical shape as
depicted in FIG. 16(d) or the circumferentially continuous thread
38 can be formed as depicted in FIG. 19(c). The opening having the
reverse conical frustum shape is oversized relative to the
auxiliary thread while the lower half portion of any through-hole
is undersized relative to the auxiliary thread and the diameter
thereof is increased by the advancement of the auxiliary
thread.
[0210] For any through-hole, the auxiliary thread taps the threaded
hole that has a substantially small back clearance using the
self-tapping action whose torque is gradually increased against the
hole-defining wall face. The partial undersize of the through-hole
creates the restraint state of the desired strength reducing the
increase of the torque. Similarly to the case of FIGS. 9(c) and
9(d) of, the self-tapping action of the screw anchor enables the
advancement that is inclined against the axis line of the reverse
conical frustum through-hole.
[0211] This facilitates the pulling of the fractured bone piece to
the convenient direction and the fine adjustment of the orientation
of the fractured bone piece. When the circumferentially continuous
thread is tapped, the advancement of the auxiliary thread creates
the restraint state of the desired strength reducing the increase
of the torque.
[0212] The upper portion of the through-hole is widened, as
depicted in FIG. 18(d), so that the accommodation of the head
portion 12 of the screw anchor is also excellent and an increase of
the created angle is facilitated. The increase of the torque for
operation is reduced and the fine adjustment of the fractured bone
piece to the desired state is executed, and effects are achieved
such as avoidance of employment of any intermittent thread and
avoidance of the necessity of any screw insert.
[0213] The examples depicted in FIGS. 15(b) and 15(c) are each the
example where the enveloping surface of the tooth tips lining on
and beneath the auxiliary thread 13 is set to have a partially
spherical shape. In the former case, a center 40 of the lower half
spherical face is present on the axis line 5a of the screw anchor
and, in the latter case, a center 40A is positioned in the anchor
but is out of the axis line. Though not depicted, the sphere center
can be selected to be positioned out of the anchor.
[0214] In this case, the lower half portion of the through-hole may
be set to have a partial spherical face as depicted in FIG. 20(b)
or a thread may be tapped on this face. As depicted in FIGS. 20(c)
and 20(d), the spherical enveloping surface-like screw teeth
achieve the desired restraint suppressing any rapid increase of the
torque during the use of the self-tapping action for the radius
locking plate. The spherical face further increases the degree of
freedom of the advancement direction.
[0215] The screw anchor cannot use the self-tapping action for the
metal radius locking plate. In the present invention utilizing the
relation between a metal and a non-metal, the self-tapping is
however used. The inventors assured that no problem arose in
securing the initial screw-fixation strength and in the change over
time of the strength using a bending strength test acted on the
screw anchor, or the like. For example, the principal thread was
bent of the screw anchor screw-fixed to the circumferentially
continuous thread.
[0216] No problem arose when the bending was bending in the
direction of an arrow 41 in FIG. 21(d) even in the case where the
axis line of the auxiliary thread 13 matched with that of the
through-hole 6 as depicted in FIG. 21(b) or even in the case where
the axis line of the auxiliary thread 13 did not match with that of
the through-hole 6 as depicted in FIG. 21(c). The case where a
problem arose was the case where bending in the direction of an
arrow 42 in FIG. 21(d) was applied. This was the bending in the
direction to fill up a gap 43 formed between the circumferentially
continuous thread and the auxiliary thread.
[0217] Any bending-back against the bending however cannot occur
during the surgical operation and after the surgical operation.
When one screw anchor is advanced being inclined, the presence is
indispensable of other screw anchors firmly standing for (applying
counter-forces to) each other. As a result, any degradation of the
strength due to the bending-back can therefore be ignored. It was
assured that any bending in each of the directions other than this,
that is, the directions approaching the reader and leaving the
reader that are perpendicular to the page surface including the
arrow 41 caused no problem.
[0218] The increase of the diameter of the undersized thread formed
in the through-hole by the auxiliary thread will be described. It
is assumed that the auxiliary thread has the cylindrical shape.
FIG. 22(a) depicts an undersized threaded hole 6A. FIG. 22(b)
depicts a threaded hole 6B that has a diameter increased. FIG.
22(c) depicts the state where the auxiliary thread 13 is advanced
to the middle of the threaded hole 6A and the diameter of the lower
half portion is not yet increased. FIG. 21 depicts an example of
the case where the opening 6b of the through-hole has a reverse
conical frustum shape. A shaded portion 44 disappears by the
increase of the diameter of the threaded hole as depicted in FIG.
21(a) while the hole-defining wall becomes substantially packed by
the auxiliary thread.
[0219] FIG. 23 depicts the forms of the undersize of the
circumference direction continuous screw 38. In both of FIGS. 23
(a) and 23(b), the valley-bottom diameter and the inner diameter of
the threaded hole after the increase of the diameter are both
increased relative to those before the increase of the diameter
indicated by thin lines. Not to mention, the pitch of the
undersized threaded hole is imparted to be equal to the pitch of
the auxiliary thread while, in FIG. 23(a), a height h.sub.6 of the
thread of the undersized hole is equal to a height h.sub.13 of the
thread of the auxiliary thread. In FIG. 23(b), the height h.sub.6
of the thread of the undersized threaded hole is lower than the
height h.sub.13 of the thread of the auxiliary thread. The volume
removed by the increase of the diameter is larger in the case of
FIG. 23(b) than that in the case of FIG. 23(a).
[0220] FIG. 23(c) depicts the case where the inner diameters are
equal to each other, and the valley-bottom diameter after the
increase of the diameter is larger than that before the increase of
the diameter, indicated by the thin lines. The difference in the
removed volume is caused only by the difference in the height.
Which one of FIGS. 23(a), 23(b), and 23(c) is employed is
determined according to the physical properties such as the
hardness and the viscosity, and the amount of the reinforced carbon
fibers of the resin of the radius locking plate.
[0221] FIG. 16(b) depicts an example where a PEEK resin is coated
on the surface of the principal thread 11 of the screw anchor (a
coating resin 45 is depicted in a dilute color). This is applicable
to any of the screw anchors while, after fully examining the state
of the radius, this coating only has to be used, for example, for
advancement and screw-fixation at the points at which soft touch is
necessary. The resin-coated metal teeth of the screw anchor reduce
the advancement load on the radius, and any breakage and any
destruction of the cortical bone is alleviated. The restrain with
the cancellous bone and that with the cortical bone is weaker than
that of the naked metal screw while the load of the after-the-fact
removal operation is alleviated.
[0222] FIGS. 24(a) to 24(c) depict an example where a thread pitch
p.sub.11 of the principal thread 11 is set to be larger than a
thread pitch p.sub.13 of the auxiliary thread 13. FIGS. 24(d) to
24(f) depict an example where the thread pitch p.sub.11 of the
principal thread 11 is set to be smaller than the thread pitch
p.sub.13 of the auxiliary thread 13. In the former case, the resin
plate can be attached to be adjacent to the radius by the
advancement of the screw anchor and, in the latter case, the resin
plate can be disengaged from the radius by the advancement of the
screw anchor. In the examples described herein, the auxiliary
thread of the screw anchor has a constant diameter while the
examples are applicable to the case of the gradually reduced
diameter described referring to FIG. 15(a).
[0223] Description will be made referring to FIGS. 24(a) to 24(c)
in this order. When the screw anchor 5 is rotated by, for example,
one round, the principal thread 11 advances by one pitch relative
to the radius 1. Due to the displacement by the one pitch of the
radius locking plate 4 relative to the auxiliary thread 13 of the
advanced screw anchor, the radius locking plate makes an approach
to the radius by the amount acquired by subtracting the one pitch
of the auxiliary thread from the one pitch of the principal thread
(=p.sub.11-p.sub.13). This is advantageous to facilitate tight
attachment at a position at which the resin plate in its bridging
state partially floats from the radius.
[0224] In FIGS. 24(d) to 24(f), when the screw anchor rotates by
one round, the principal thread advances by one pitch relative to
the radius. Due to the displacement by the one pitch of the radius
locking plate relative to the auxiliary thread of the advanced
screw anchor, the radius locking plate makes disengagement relative
the radius by the amount acquired by subtracting the one pitch of
the principal thread from the one pitch of the auxiliary thread
(=p.sub.13-p.sub.11). This facilitate the disengagement at a
position at which the resin plate in its bridging state is attached
too closely to the radius, and can cause any blood flow disorder of
the capillary blood vessels of the periosteum to tend to be avoided
by the alleviation of the close attachment.
[0225] Exemplary one of examples of the former is depicted in FIG.
25 and FIG. 26 and that of the latter is depicted in FIG. 27. All
the thread pitches each in the hole having the thread tapped
therein only have to be set to be same that each are p.sub.13 for
the through-holes of the radius locking plate. The size of the
thread pitch p11 of the principal thread of the screw anchor only
has to be the one selected based on the determination by the
operator.
[0226] FIG. 25 and FIG. 26 depict an example of the procedure for
fixing the radius locking plate 4, depicted to exaggerate the gap
remaining in the distal end. FIG. 25(a) is a diagram of tentative
clamping depicting the state where an excessive bending gap 46
appears between a virtual recovered fractured bone piece 2i and the
distal end of the radius locking plate 4 attached to the radius
main body 3 due to the screw-fixation of a tentatively clamping
screw 5T.
[0227] FIG. 25(b) is a diagram of lifting up of the fractured bone
piece 2 by the screw anchor 5A including the principal thread
having the thread pitch p.sub.11 that is larger than the thread
pitch p.sub.13 of the auxiliary thread. In this case, the fractured
bone piece is closely attached to the radius locking plate and the
excessive bending gap disappears while a fracture gap 47 at a
position becomes widened as the position becomes more distant from
the radius locking plate.
[0228] FIG. 25(c) depicts the state where the fractured bone piece
2 is pulled toward the radius main body 3 by somewhat moving the
tentatively clamped radius locking plate toward the elbow of a
white arrow 21. FIG. 25(d) depicts the state where the vicinity of
the through-hole is loosely fixed to the radius main body 3 by
driving the screw anchor 5M into the radius main body at the
position closest to the fractured bone piece, and the tentatively
clamping screw 5T is also somewhat loosened as necessary.
[0229] In FIG. 26(a), the radius locking plate 4 is caused to
partially be disengaged from the radius 1 in a direction of an
arrow 48B by a screw anchor 5N including the principal thread
having the thread pitch p.sub.11 that is smaller than the thread
pitch p.sub.13 of the auxiliary thread screw-advancing in another
through-hole close to the elbow. The distal end of the radius
locking plate using a screw anchor 5M closest to the fracture bone
piece as the fulcrum swivels in a direction of an arrow 48C. FIG.
26(b) is a diagram of substantial leveling of the fracture gap 47.
FIG. 26(c) is a diagram of the locking completion state where the
necessary number of other screw anchors 5B are fixed in the radius
locking plate.
[0230] FIG. 27 depicts an example of the procedure for fixing the
radius locking plate 4, depicted exaggerating the gap at the
teardrop recess. FIG. 27(a) is a diagram of tentative clamping
state where an insufficient-bending gap 49 remains at the teardrop
recess 53 in the radius locking plate 4 attached to the radius main
body 3 due to the screw-fixation of the tentatively clamping screw
5T.
[0231] FIG. 27(b) is a diagram of lifting up of the fractured bone
piece by the screw anchor 5A including the principal thread having
the thread pitch that is larger than the thread pitch of the
auxiliary thread and, in this case, a fracture gap 47A becomes
widened at a position as the position becomes closer to the radius
locking plate when the fractured bone piece is closely attached to
the radius locking plate. FIG. 27(c) is a diagram of the state
where the fractured bone piece 2 is pulled toward the radius main
body 3 to shrink the fracture gap 47 in its entirety by moving the
tentatively clamped radius locking plate toward the elbow of the
white arrow 21.
[0232] FIG. 27(d) is a diagram of swiveling of the distal end of
the radius locking plate by closely attaching the radius locking
plate to the radius by the advancement of a screw anchor 5AA
including the principal thread having the thread pitch larger than
the thread pitch of the auxiliary thread in the through-hole in the
portion having the insufficient-bending gap 49 remaining therein.
The close attachment in a direction of an arrow 48D causes the
swivel in a direction of an arrow 48E to substantially level the
fracture gaps 47A. The desired number of other screw anchors 5B are
fixed to the radius locking plate to complete the locking.
[0233] It can be seen that the fitting property of the radius
locking plate for the radius can be improved by the above
operation. The operation causes bending of the radius locking plate
using the advancement, and this bending is an impossible behavior
by any metal plate. As repeatedly described, compared to any metal
radius locking plate, as to the resin radius locking plate, any
deformation at the desired point can be coped with by the
advancement operation of the thread and by the after-the-fact
heating to deform a lined-up product as above and it is therefore
understood that the flexibility thereof is beyond comparison with
that of any metal plate. Though the above operation is more
meaningful in the case of a fracture of the ulna, the details
thereof will not be described.
[0234] As depicted in FIG. 28, with a screw anchor 5R whose
principal thread 11 has the thread pitch p.sub.11 that is equal to
the thread pitch p.sub.13 of the auxiliary thread 13 thereof, even
when the screw anchor advances, no behavior is executed to widen or
narrow a facing gap 6 between the radius locking plate and the
radius. In the examples of FIG. 25 and FIG. 27, this is applicable
to the screw anchors 5M and 5B.
[0235] The elements and the combinations thereof described in the
present invention will additionally be described. The elements will
be simply denoted by a letter "C" and a subsequent three-digit
number. [0236] C011: The radius locking plate is a flat laminate of
intermediate molding materials each including carbon fibers as
reinforcing material and thermoplastic resin as a matrix. [0237]
C012: The screw anchor is made of hard metal and the shaft portion
thereof has a principal thread achieving a self-tapping action
formed thereon while the outer circumference of the head portion
thereof also has an auxiliary thread achieving a self-tapping
action tapped thereon. [0238] C013: The diameter of a through-hole
in the radius rocking plate to fix the radius main body and a
fractured bone piece is oversized relative to the principal thread
and is undersized in the through-hole in its entirety or in the
lower half portion relative to the auxiliary thread. [0239] C021:
The intermediate molding material reinforced by the carbon fibers
of the 45.degree.-orientation material or the
.+-.45.degree.-orientation woven cloth is used in the upper layers
and the lower layers of the radius locking plate, and intermediate
molding materials each reinforced by the carbon fibers of a
one-direction material or a 0.degree./90.degree.-orientation woven
cloth are used in the intermediate layer. [0240] C031: The
through-hole has the cylindrical shape. [0241] C041: The
cylindrical through-hole is oversized in the upper half portion
thereof relative to the principal thread and is undersized in the
lower half portion thereof relative to the auxiliary thread. [0242]
C051: The cylindrical through-hole has a circumferentially
continuous thread that has a diameter to be increased by the
auxiliary thread, tapped in the through-hole in its entirety or in
the upper half portion thereof. [0243] C061: The through-hole has a
reverse conical frustum shape in at least its opening. [0244] C071:
The lower half portion of the through-hole has a cylindrical shape
and has a diameter increased by the auxiliary thread. [0245] C081:
The lower half portion of the through-hole has the
circumferentially continuous thread tapped therein that has a
diameter to be increased by the auxiliary thread. [0246] C091: The
through-hole has a reverse conical frustum shape in its entirety,
and the through-hole has a circumferentially continuous thread
tapped in its entirety or its lower half portion, the
circumferentially continuous thread has a diameter to be increased
by the auxiliary thread. [0247] C101: The lower half portion of the
through-hole has a partially spherical shape. [0248] C111: The
auxiliary thread has an enveloping surface of the tooth tips lining
thereon and therebeneath forming a partially spherical shape.
[0249] C121: The auxiliary thread has an enveloping surface of the
tooth tips lining thereon and therebeneath forming a reverse
conical frustum shape. [0250] C131: A PEEK resin is coated on the
surface of the principal thread of the screw anchor. [0251] C141:
The thread pitch of the principal thread is larger than the thread
pitch of the auxiliary thread of the screw anchor. [0252] C151: The
thread pitch of the principal thread is smaller than the thread
pitch of the auxiliary thread of the screw anchor. [0253] C161: A
metal wire tracing the contour of the radius locking plate is
embedded in the edge portion of this plate. [0254] C171: An
intermediate molding material is coated to the face on the radius
counter-approximal face of the flat laminate of the intermediate
molding materials. [0255] C181: A non-reinforced resin is applied
to the face on the radius counter-approximal face of the flat
laminate of the intermediate molding materials. [0256] C191: The
non-reinforced resin is applied to the face on the radius
approximal face of the radius locking plate. [0257] C201: Small
protrusions are provided on the face on the radius approximal face
of the radius locking plate. [0258] C211: To provide the small
protrusions, the positions corresponding to the small protrusions
of the flat laminate are defined by a PEEK resin compound layer.
[0259] C221: The lateral cross-sectional shape of the radius
locking plate is set to be a substantially crescent shape. [0260]
C231: The bending of the radius locking plate is provisionally set
and typical plural radius locking plates having different lengths
and different widths are lined up as semi-finished products. [0261]
C241: A finished product of the radius locking plate is a
bending-corrected product that is formed by partially heating the
semi-finished product to adapt the distal portion point thereof to
the teardrop recess of the radius for application.
[0262] The elements and the combinations thereof described in the
present invention are also realized in the following cases. [0263]
[1] Addition of any one element or a combination of any plural
elements of C121, C131, C141, C151, C161, C171, C181, C191, and
C201 to an invention including C011, C012, and C013 (hereinafter,
collectively referred to as "C01T") and C021 (hereinafter,
collectively referred to as "C12-20T"). [0264] [2] Addition of
C12-20T also to an invention that includes C01T, C021, and C031.
[0265] [3] Addition of C10-20T also to an invention that includes
C01T, C021, C031, and C041. [0266] [4] Addition of C12-20T also to
an invention that includes C01T, C021, C031, and C051. [0267] [5]
Addition of C12-20T to an invention that includes C01T, C021, and
C061. [0268] [6] Addition of C12-20T also to an invention that
includes C01T, C021, C061, and C071. [0269] [7] Addition of C12-20T
also to an invention that includes C01T, C021, C061, C071, and
C081. [0270] [8] Addition of C12-20T to an invention that includes
C01T, C021, C061, and C091. [0271] [9] Addition of C12-20T to an
invention that includes C01T, C021, C061, and C101. [0272] [10]
Addition of C12-20T to also an invention that includes C01T, C021,
C061, C101, and C111. [0273] [11] Addition of C211 to an invention
that includes C01T, C021, and C201. [0274] [12] Addition of C12-20T
and/or C211 also to an invention that includes C01T, C021, and
C221.
* * * * *